Method and apparatus for alerting an operator of a motor vehicle to an incoming radar signal

ABSTRACT

A radar detector for alerting an operator of a motor vehicle to an incoming police radar signal. This radar detector includes a microprocessor; a circuit coupled to the microprocessor for detecting the incoming police radar signal; and a global positioning system receiver coupled to the microprocessor. Upon detection of an incoming radar signal, the radar detector can utilize the position, velocity, and/or heading data from the global positioning system receiver to determine whether to generate an alert.

1. BACKGROUND

The present invention relates generally to police radar detectors usedin motor vehicles and, more particularly, to police radar detectors thatutilize a motor vehicle's position, velocity and/or heading to minimumfalse alarms.

Many operators of motor vehicles utilize radar detectors to alert themto the fact that their speed is being monitored by law enforcementagencies. However, conventional radar detectors often generate “falsealarms.” These false alarms are annoying to the operators of motorvehicles. In fact, various automotive publications publish results of“false alarm” tests. Thus, anything that can be accomplished by themanufacturer to reduce the number of false alarms without reducingdetection of police radar is commercially valuable.

In addition to police radar signals, there are many different sources ofmicrowave signals in the frequency bands allocated to police radar bythe U.S. Federal Communications Commission (FCC). For example,motion-detecting burglar alarms and automatic door openers also operatein the frequency bands allocated to police radar. Thus, a need existsfor a radar detector that can distinguish between signals generated by apolice radar transmitter and those generated by other devices whichutilize microwave signals within the same frequency bands.

Still another source of annoying false alarms occurs when an operator ofa motor vehicle is travelling at a speed that is below the legal speedlimit, such as occurs when the operator is in traffic, and the radardetector alerts him to an incoming radar signal. Even if a police radarsignal is monitoring the speed of the operator's vehicle, because thevelocity of the vehicle is below the legal speed limit, the operator ofthe vehicle may not need to be alerted to the presence of the policeradar signal. Thus, a need exists for a radar detector that does notgenerate an alert if the velocity of the radar detector is below thelegal speed limit.

Operators have become accustomed to radar detectors activating incertain locations along commonly traveled streets and highways. Policeradar units may be deployed by the side of the roadway at theselocations since the police also are aware of the local activationsignals and the police are aware that the signals tend to mask their ownspeed monitoring radar units. Thus, a need exists for a radar detectorthat can avoid generating a false alarm due to such accustomed radarsignals while still generating an alert for such police radar signals.

2. SUMMARY OF THE INVENTION

One embodiment is a radar detector for alerting an operator of a motorvehicle to an incoming police radar signal. This radar detector includesa microprocessor; a circuit coupled to the microprocessor for detectingthe incoming police radar signal; and a global positioning systemreceiver coupled to the microprocessor. The radar detector also includesa program storage device containing instructions for determining whetherto generate an alert to an incoming radar signal based upon the radardetector's position, velocity, and/or heading.

Another embodiment of the invention is a method of generating an alertto an incoming radar signal. This method includes first detecting theincoming radar signal. Next, the position of a radar detector isdetermined. Then, an alert is generated if the position of the radardetector is not within a predetermined distance of a predeterminedposition.

Still another embodiment of the invention is a second method ofgenerating an alert to an incoming radar signal. This method includesfirst detecting the incoming radar signal. Next, the velocity of theradar detector is determined. Then, an alert is generated if thevelocity of a radar detector is greater than a predetermined velocity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram of a radar detector including one embodimentof the present invention.

FIG. 2 is a flow diagram of a method of operating a radar detector.

FIG. 3 is a flow diagram of another method of operating a radardetector.

FIG. 4 is a flow diagram of yet another method of operating a radardetector.

3. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

3.1 Description of a First Embodiment

One embodiment of the novel radar detector is shown in FIG. 1. The radardetector includes an antenna that is coupled to a detector circuit. Thedetector circuit, which may be controlled by the microprocessor of FIG.1, collects the signals from the antenna, detects the incoming signals,and distinguishes valid radar signals from electrical noise. Thedetector circuit may be any appropriate radar detector circuit capableof generating an output signal which indicates the strength, thepresence, and/or the frequency of incoming radar signals. While thedetector circuit may operate autonomously, operation and control of thedetector circuit may be performed by the microprocessor. For example,the microprocessor may control the detector as is known in the art sothat radar signals in the different frequency bands allocated to policeradar signals are detected. Such detector circuits can take a widevariety of forms and can include amplifiers, mixers, duplexes, and othercircuitry commonly used in the radar detector field. Several examples ofsuch circuits are shown in U.S. Pat. Nos. 4,313,216, 5,068,663, and5,250,951, which are incorporated herein by reference.

The output of the detector circuit is coupled to the input of one ormore analog-to-digital converters. These converters convert the analogoutput of the detector circuit into digital signal that represent signalstrength, signal presence, and/or signal frequency.

In addition to being coupled to the detector circuit and theanalog-to-digital converter, the microprocessor is also coupled to analert circuit. The alert circuit communicates information regardingdetected radar signals to the operator of a motor vehicle using theradar detector by means of one or more alarm tones and/or visualindicators that are included within the alert circuit. Alert circuitsare known by those skilled in the art. For example, see U.S. Pat. Nos.4,313,216, 5,068,663, and 5,250,951, which are incorporated herein byreference.

The microprocessor, which may be any conventional single or multiplechip microprocessor or digital signal processor, is coupled to a programstorage device. The program storage device may be any conventionalmemory device such as a PROM, EPROM, EEPROM, ROM, SRAM, or even batterybacked up DRAM. The program storage device contains machine readableinstructions that command the microprocessor to perform certainfunctions. For example, the program storage device may be conventionallyprogrammed to sweep a predetermined number of radar frequency bands,determine the frequency and/or signal strength of any detected radarsignals in the swept frequency bands, and, if the signal strength of thedetected radar signals exceed a predetermined value, then generate asignal that activates the alert circuit. Such programming is known bythose skilled in the art. For example, see U.S. Pat. Nos. 4,313,216,5,068,663, and 5,250,951, which are incorporated herein by reference.

The microprocessor is also coupled to a positioning system such as aglobal positioning system (“GPS”) receiver. As is well known, a GPSreceiver receives signals from satellites and uses these signals tocalculate the position of the GPS receiver. In addition, the GPSreceiver may receive differential correction data and/or dead reckoningdata, such as from a compass or a wheel sensor, to increase the accuracyof the receiver. By calculating the position of the GPS receiver at twodifferent times, the velocity and heading of the GPS receiver can beeasily determined using conventional algorithms. Thus, the GPS receivercan provide the microprocessor with data that includes the position, thevelocity, and/or the heading of the radar detector.

The microprocessor may also be coupled to a user interface circuit (notshown). The user interface circuit may include a plurality of buttonsthat are intended to be depressed by an operator of a motor vehicle.Such buttons may include: a power button, a mute button, a city/highwaybutton, and a dim button.

As will be discussed more fully below, the program storage device mayalso contain machine readable instructions that command themicroprocessor to determine whether to generate an alert based upon datareceived from the GPS. Thus, upon detection of an incoming radar signal,the radar detector can utilize the position, velocity, and/or headingdata from the global positioning system receiver to determine whether togenerate an alert.

3.2 Description of a Second Embodiment

One method of operating the radar detector of FIG. 1 is shown in FIG. 2.In this embodiment, the radar detector first detects an incoming radarsignal. Next, the position of the radar detector is determined. Then, analert is generated if the position of the radar detector is not within apredetermined distance of a predetermined position.

By utilizing the above method, many false alarms may be eliminated. Forexample, if the position of a microwave automatic door opener isprogrammed into the radar detector and the radar detector detects anincoming signal when the radar detector's position is near the automaticdoor opener, then it is likely that the source of the incoming radarsignal is the automatic door opener and not a police radar. Thus, usingthe method of FIG. 2, an alert would not be generated for the detectorradar signal.

The programming of predetermined positions may be accomplished bydepressing one or more buttons that are coupled to the interface circuitdiscussed above. Thus, if an operator of a motor vehicle approaches amicrowave automatic door opener, then the operator can depress an“ignore radar” button. Then, the radar detector would store the positionof the radar detector and possibly the frequency and the signal strengthof the incoming radar signal in the program storage device of FIG. 1 oranother memory device (not shown) coupled to or integrated within themicroprocessor. An alternative method of storing such data would be tohold down a “mute” button for an extended length of time such as 3 to 5seconds. It is also possible to experimentally generate a databasecontaining position, frequency and/or signal strength for a specificgeographical region. This database could be provided to operators ofmotor vehicles for a fee. Accessing the Internet via a cellular phone(not shown) coupled to the microprocessor of FIG. 1 would be one methodof providing the above database to operators of motor vehicles.

In still another embodiment, when the operator instructs the radardetector to store a position of a incoming radar signal, the radardetection could attempt to locate the approximate position of the sourceof the incoming radar signal. For example, if an operator instructs theradar detector to store a position of an incoming radar signal as theoperator is still approaching the source of the incoming radar signal,the signal strength of the incoming radar signal will be increasing. Theradar detector could locate a position that is very near the position ofthe source of the incoming radar signal by determining the position ofthe radar detector when the strength of the incoming signal is at amaximum. In addition, radar detectors such as described in U.S. Pat. No.5,250,951, may utilize multiple radar antennas and signal processinglogic to more accurately determine the position of the source of theincoming radar signal. For example, the position of the source of manyincoming radar signals may be closely approximated by the position of aradar detector when the radar detector identifies that the radar sourceis to the side of the vehicle.

The predetermined distance may also be programmed by the operator of themotor vehicle. If the GPS receiver is receiving differential correctiondata or is receiving dead reckoning data, then the predetermineddistance may be set to a smaller value because the position of the radardetector may be more precisely determined. In addition, if the strengthof the incoming radar is strong, the predetermined distance could be set(manually or automatically) to a higher value because the radar detectorwill detect the incoming radar signal at a greater distance from thesource. For example, if a radar detector in a vehicle detected a radarsignal while the vehicle traveled a 1 mile distance, then thepredetermined distance for that particular radar signal may becalculated by dividing the 1 mile distance in half. In order tocompensate for non-symmetrical detection of the radar signal andinaccuracies of the positioning of the radar detector, an additional ¼or ½ mile might be added to the above predetermined distance.

3.3 Description of a Third Embodiment

The simple method of operating a radar detector shown in FIG. 2 can beimproved as shown in FIG. 3. In this embodiment, the after the radardetects an incoming radar signal it determines a characteristic of theradar signal. For example, the radar detector may determine thefrequency and/or the signal strength of the incoming radar signal. Next,the position of the radar detector is determined. Then, an alert isgenerated if the radar detector is not within a predetermined distanceof a predetermined position and the characteristic is not similar to apredetermined characteristic.

By utilizing this method, many false alarms may be eliminated. Forexample, the location of a microwave automatic door opener and thefrequency of the radar signal transmitted by the door opener are firstprogrammed into a radar detector. Assume that a police radar is beingtransmitted near the location of the microwave automatic door opener.Because the police radar is near the automatic door opener, the methodof FIG. 2 would not generate an alert. Thus, the operator of amotor-vehicle would not be properly alerted to the police radar. Howeveras shown below, the method of FIG. 3 would generate an alert.

If the automatic door opener signal is processed first according to themethod of FIG. 3, then the frequency of the automatic door opener signalwould be determined. Next, the position of the radar detector would bedetermined. Because the radar detector is near the previously programmedposition of the automatic door opener and the frequency of the incomingradar signal is equal to the previously programmed frequency of theautomatic door opener, the radar detector would not generate an alert.

Next, the police radar signal would be processed. Thus, the frequency ofthe police radar signal would be determined. However, even though thelocation of the radar detector is near the previously programmedlocation of the automatic door opener, because the frequency of thepolice radar is not equal to the previously programmed frequency of theradar signal transmitted by the door opener, an alert would begenerated. Thus, the operator of the motor vehicle would be properlyalerted to the presence of the police radar signal.

Due to inaccuracies in algorithms and slight variations in frequenciesdue to physical phenomena such as temperature of radar transmitters, itmay not be practical to determine if a frequency of an incoming signalis exactly equal to a previously programmed frequency. Thus, is oftensufficient to determined if the frequency of an incoming radar signal issimilar to a previously programmed frequency. For example, if twofrequencies are within ½, 1, 2, 3, 4, or 5 MHz of each other, then theymay be considered to be similar.

In one embodiment of the invention, 256 frequency bins are defined foreach frequency band of the radar detector. Thus, this one embodiment ofthe invention, each of the following frequency bands would have 256bins: X band (10.475-10.575 GHz); Ku band (13.400-13.500 GHz); K band(24.025-24.275 GHz); and Ka band (34.150-35.250 GHz). In thisembodiment, frequencies are considered to be similar if they are in thesame frequency band and are in the same bin. In still anotherembodiment, frequencies are considered to be similar if they are in thesame frequency band and are in the same or adjacent bins. In these twoembodiments, the exact frequency of the incoming radar signal need notbe determined. Only the frequency band and the appropriate frequency binnumber need be determined. If higher resolution is required, then thenumber of bins for one or more frequency bands can be increased. On theother hand, if only very low resolution is required, then if twofrequencies are in the same frequency band, they may be considered to besimilar.

3.4 Description of a Fourth Embodiment

FIG. 4 shows still another method of operating the radar detector ofFIG. 1. In this embodiment, the radar signal is first detected. Then,the velocity of the radar detector is determined. Next, an alert isgenerated if the velocity of the radar detector is greater than apredetermined velocity.

This embodiment is particularly useful if the predetermined velocity isset to a value that is less than the minimum speed time. For example, ifan operator of a motor vehicle programs the predetermined velocity to 65miles per hour, which may be the speed limit on a particular highway,then the operation will not be alerted to a radar signal unless he isspeeding. Thus, the operator will not be alerted to radar signals whenhe is traveling at a slow rate of speed such as when the operator is intraffic. The operator could also program the predetermined velocity tothe minimum speed limit that the operator is likely to encounter in aspecific geographical region. For example, if the city in which theoperator lives has some streets with a 25 miles per hour speed limit,then the operator could program the predetermined speed to 25 miles perhour. If the operator performed such programming, such as by decreasingone or more buttons that are coupled to the interface circuit, theoperator could be spared some, but not all false alarms.

A more sophisticated embodiment would not require the user to manuallyprogram the speed limit. This embodiment would obtain the speed limitfrom a database that contains speed limits for particular roads in ageographical region. By comparing the location and/or the heading of amotor vehicle to the location and/or heading of a plurality of roads inthe above database, the radar detector could determine the particularroad upon which the vehicle is traveling. After such a determination,the speed limit for the particular road could be accessed from thedatabase. Such algorithms are known by those skilled in the art. Thisdatabase could be stored on the program storage device of FIG. 1 orcould be stored on an external storage device such as a CD ROM or a harddisk drive. This database could also be provided to operators of motorvehicles for a fee.

3.5 Other Embodiments

In some cases, an operator of a motor vehicle may desire to be alertedto the presence of a radar signal even if the above methods would not“generate an alert.” In such cases, a less intrusive alert such as areduced volume tone, and/or a flashing LED could be generated. Thus, thephrase “generate an alert if” a condition occurs is intended to includegenerating a particular alert if the condition occurs. If anothercondition occurs, such as detection of an incoming radar signal whilethe radar detector is within a predetermined distance of a predeterminedposition as shown in FIG. 2, then another alert may be generated.

The above Description of the Preferred Embodiments includes words, suchas “first,” “then,” and “next.” These words indicate a sequence of acts.Many of the sequences can be modified within the scope of the invention.Thus, unless the results of a first act is required for a second act,then the language indicating a sequence should not be considered to belimitations to the invention.

Many of the above embodiments can be combined to produce a radardetector that generates very few false alarms. For example, the methodsof FIG. 2 or FIG. 3 can be combined with the method of FIG. 4. Suchcombinations are intended to be within the scope of the invention.

1. A method, executed by a device having a position, of generating analert to an incoming radar signal having a frequency and a signalstrength, the method comprising the acts of: (a) detecting the incomingradar signal; (b) determining the position of the device that detectedthe incoming radar signal; and (c) generating an alert if the positionof the device is not within a predetermined distance of a predeterminedposition.
 2. The method of claim 1 wherein the act of detecting theincoming radar signal includes determining at least one characteristicof the radar signal.
 3. The method of claim 2 wherein the act ofdetermining at least one characteristic of the radar signal includesdetermining the frequency of the radar signal.
 4. The method of claim 2wherein the act of determining at least one characteristic of the radarsignal includes determining a frequency bin number.
 5. The method ofclaim 2 wherein the act of determining at least one characteristic ofthe radar signal includes determining whether the incoming radar signalis in the X frequency band, the Ku frequency band, the K frequency band,or the Ka frequency band.
 6. The method of claim 2 wherein the act ofdetermining at least one characteristic of the radar signal includesdetermining the signal strength of the incoming radar signal.
 7. Themethod of claim 2 wherein the act of generating an alert includesgenerating an alert if the at least one characteristic is not similar toa predetermined characteristic.
 8. The method of claim 1 wherein the actof determining the position of the device includes receiving signalsfrom a plurality of satellites.
 9. The method of claim 1 wherein the actof determining the position of the device includes receiving adifferential global positioning signal.
 10. The method of claim 1wherein the act of determining the position of the device includesreceiving dead reckoning data.
 11. A method, executed by a device havinga position and a velocity, of generating an alert to an incoming radarsignal having a frequency and a signal strength, the method comprisingthe acts of: (a) detecting the incoming radar signal; (b) determiningthe velocity of the device that detected the incoming radar signal; and(c) generating an alert if the velocity of the device is greater than apredetermined velocity; (d) determining the position of the device thatdetected the incoming radar signal; and (e) comparing the position ofthe device that detected the incoming radar signal to a predeterminedposition.
 12. The method of claim 11 wherein the act of determining thevelocity of the device includes receiving data from a plurality ofsatellites.
 13. The method of claim 11 wherein the act of determiningthe velocity of the device includes receiving data from a plurality ofglobal positioning satellites.
 14. The method of claim 11 wherein theact of determining the velocity of the device includes receivingdifferential global positioning data.
 15. The method of claim 11 whereinthe act of determining the velocity of the device includes receivingdead reckoning data.
 16. The method of claim 11 wherein the act ofgenerating an alert if the velocity of the device is greater than apredetermined velocity includes generating an alert if the velocity ofthe device is greater than a velocity that has been previouslyprogrammed by an operator of a motor vehicle.
 17. The method of claim 11wherein the act of generating an alert if the velocity of the device isgreater than a predetermined velocity includes generating an alert ifthe velocity of the device is greater than a legal speed limit that isretrieved from a database.
 18. A radar detector for alerting an operatorof a motor vehicle to an incoming police radar signal comprising: (a) amicroprocessor; (b) a circuit coupled to the microprocessor fordetecting the incoming police radar signal; and (c) a global positioningsystem receiver coupled to the microprocessor and operable to providethe microprocessor with data that indicates the position of the radardetector.
 19. The radar detector of claim 18, further including A radardetector for alerting an operator of a motor vehicle to an incomingpolice radar signal comprising: (a) a microprocessor; (b) a circuitcoupled to the microprocessor for detecting the incoming police radarsignal; (c) a global positioning system receiver coupled to themicroprocessor and operable to provide the microprocessor with data; and(d) a program storage device that is coupled to the microprocessor, theprogram storage device containing machine readable instructions for:(a)(i) determining the position of a radar detector; and (b)(ii)generating an alert if the position of the radar detector is not withina predetermined distance of a predetermined position.
 20. The radardetector of claim 19, wherein the program storage device includesmachine readable instructions for determining at least onecharacteristic of the radar signal.
 21. The radar detector of claim 18,further including a program storage device that is coupled to themicroprocessor, the program storage device containing machine readableinstructions for: (a) determining the velocity of the device utilized todetect the incoming radar signal; and (b) generating an alert if thevelocity of a radar detector is greater than a predetermined velocity.22. The method of claim 1, further comprising: (d) generating the alertif the device is within the predetermined distance of the predeterminedposition and if the signal strength of the incoming radar signal isgreater than a predetermined radar signal strength.
 23. The method ofclaim 1, further comprising: (d) generating the alert if the device iswithin the predetermined distance of the predetermined position and ifthe signal strength of the incoming radar signal is not within apredetermined frequency range of a predetermined radar frequency. 24.The method of claim 1, further comprising: (d) generating the alert ifthe device is within the predetermined distance of the predeterminedposition and if either the signal strength of the incoming radar signalis greater than a predetermined signal strength or if the frequency ofthe incoming radar signal is not within a predetermined frequency rangeof a predetermined radar frequency.
 25. The method of claim 1, furthercomprising: (d) generating the alert if the position of the device iswithin the predetermined distance of the predetermined position.
 26. Themethod of claim 1, further comprising: (d) storing the position of thedevice in a memory device.
 27. The method of claim 1, furthercomprising: (d) storing the frequency of the incoming radar signal in amemory device.
 28. The method of claim 1, further comprising: (d)storing the signal strength of the incoming signal in a memory device.29. The radar detector of claim 18, wherein the global positioningsystem receiver is operable to provide the microprocessor with data thatindicates the velocity of the radar detector.
 30. The radar detector ofclaim 18, wherein the global positioning system receiver is operable toprovide the microprocessor with data that indicates the heading of theradar detector.
 31. The radar detector of claim 18, further comprising:(d) a program storage device that is coupled to the microprocessor, theprogram storage device containing machine readable instructions for: i)storing the position of the radar detector.
 32. The radar detector ofclaim 18, further comprising: (d) a program storage device that iscoupled to the microprocessor, the program storage device containingmachine readable instructions for: i) determining the position of asource of a radar signal; and ii) storing the position.
 33. The radardetector of claim 18, further comprising: (d) a program storage devicethat is coupled to the microprocessor, the program storage devicecontaining machine readable instructions for: i) determining thedistance between the position of the radar detector and anotherposition.
 34. The radar detector of claim 18, further comprising: (d) aprogram storage device that is coupled to the microprocessor, theprogram storage device containing machine readable instructions for: i)determining the bearing between the position of the radar detector andanother position.
 35. The radar detector of claim 18, furthercomprising: (d) a memory device that is coupled to the microprocessor,the memory device containing at least one position.
 36. The radardetector of claim 18, further comprising: (d) a memory device that iscoupled to the microprocessor, the memory device containing at least oneradar frequency.
 37. The radar detector of claim 18, further comprising:(d) a memory device that is coupled to the microprocessor, the memorydevice containing at least one radar signal strength.
 38. The radardetector of claim 18, further comprising: (d) a memory device that iscoupled to the microprocessor, the memory device containing at least oneposition and at least one radar frequency.
 39. The radar detector ofclaim 18, further comprising: (d) a memory device that is coupled to themicroprocessor, the memory device containing at least one position andat least one radar signal strength.
 40. The radar detector of claim 18,further comprising: (d) a memory device that is coupled to themicroprocessor, the memory device containing at least one position, atleast one radar frequency, and at least one radar signal strength. 41.The radar detector of claim 18, further comprising: (d) a programstorage device that is coupled to the microprocessor, the programstorage device containing machine readable instructions for: i)comparing the frequency of an incoming radar signal with a previouslystored radar frequency.
 42. The radar detector of claim 18, furthercomprising: (d) a program storage device that is coupled to themicroprocessor, the program storage device containing machine readableinstructions for: i) comparing the frequency of an incoming radar signalwith a previously stored radar frequency; and ii) generating an alertbased at least in part upon the result of the comparison.
 43. The radardetector of claim 18, further comprising: (d) a program storage devicethat is coupled to the microprocessor, the program storage devicecontaining machine readable instructions for: i) comparing the signalstrength of an incoming radar signal with a previously stored radarsignal strength.
 44. The radar detector of claim 18, further comprising:(d) a program storage device that is coupled to the microprocessor, theprogram storage device containing machine readable instructions for: i)comparing the signal strength of an incoming radar signal with apreviously stored radar signal strength; and ii) generating an alertbased at least in part upon the result of the comparison.
 45. A radardetector for alerting an operator of a motor vehicle to an incomingradar signal comprising: (a) a circuit operable to detect an incomingradar signal; and (b) a microprocessor operable to disable an alert tothe incoming radar signal based at least in part upon the position ofthe radar detector.
 46. The radar detector of claim 45, wherein themicroprocessor is operable to disable the alert based at least in partupon the velocity of the radar detector.
 47. The radar detector of claim45, wherein the microprocessor is operable to disable the alert based atleast in part upon the frequency of the incoming radar signal.
 48. Theradar detector of claim 45, wherein the microprocessor is operable toenable the alert based at least in part upon the frequency of theincoming radar signal.
 49. The radar detector of claim 45, wherein themicroprocessor is operable to disable the alert based at least in partupon the signal strength of the incoming radar signal.
 50. The radardetector of claim 45, wherein the microprocessor is operable to enablethe alert based at least in part upon the signal strength of theincoming radar signal.